“[The] No. 1 of the world is a goal for me till the end of the year, [it is] definitely an objective [and] something I [will] try to achieve,” said Djokovic.

Djokovic won his third straight China Open title in Beijing (d. Tsonga) on Sunday to further extend his lead over Roger Federer in the South African Airways ATP Rankings Race To London, with four weeks left in the regular ATP World Tour. Djokovic could return to World No. 1 next week if he wins the Shanghai title and Federer does not reach the quarter-finals.

Ahead of his media conference, Djokovic practised with Murray, his long-time friend and rival, at the penultimate ATP World Tour Masters 1000 tournament of the season.

When asked whether Murray could go on and add to his US Open title triumph, Djokovic admitted, “I don't think it's good to predict anything because tennis is such a unique sport, individual sport. A lot of factors are involved. Obviously mentally it's a matter of staying strong, staying healthy physically, trying to perform your best on a regular basis.

“He won his first Grand Slam. He could have won it already a couple years ago. He's a quality player. He's [been] one of the best players in the world in the last five years, there's no question about it. He's been improving ever since he got to professional tennis. He definitely is a contender to win all the Grand Slams, there's no question about it.”